I would be very surprised if WB was in the process of a total switching to Revit.... utterly unfeasible for the company of this size.... but I can just speculate as you do...
I have said this somewhere on this forum sometime ago:
one proprietary format will not ever work in building industry just because of the shear number of consultants and trades involved. Each of them prefers to use bespoke software. I do not want to end up with a scenario where I would be forced to choose e.g. an engineer just because they use a particular proprietary platform as opposed to their professional capabilities.
Yes it is true that IFC is not really there however so far it is only serious option on the market. And yes translating any of the available formats carries a potential errors by default. The only way (my opinion) to control it is a full-on IFC server with standardised interface to keep integrity of data. Sure if you put sh*t in you would get sh*t out but that's a different cuppa...
BTW I have talked to a fella who runs BIMServer project in Denmark (?) (unfortunately the project is not mature enough for a serious hammering) about IFC compatibility. They ran some tests with Revit and it seems that Adesk is deliberately screwing IFC up... well I suppose GS could answer to this with some optimised and workable IFC import/export in near future perhaps.
::rk